Method of repairing leakage in pipelines

ABSTRACT

A method of repairing leakage in pipelines comprising the steps of forming a first and second openings ( 14   a,    14   b ) in the pipeline ( 10 ) upstream and downstream, respectively, of the leakage location, inserting through the first opening ( 14   a ) a first body (C 1 ), filling the space arrear of the first body (C 1 ) with a first viscose sealing material (M 1 ), inserting through the first opening ( 14   a ) a second body (C 2 ) arrear of the first viscose sealing material (M 1 ) compressing the first sealing material by applying a pressure against the first and the second bodies (C 1,  C 2 ) in opposite directions, causing the first and second bodies (C 1,  C 2 ) and the compressed first sealing material (M 1 ) to move in unison in the direction of the second opening ( 14   b ), and retrieving the first and second bodies (C 1,  C 2 ). Preferably, the method is performed using three bodies (C 1,  C 2,  C 3 ) and two sealing materials (M 1,  M 2 )

FIELD OF THE INVENTION

The present invention relates to the repair or restoration of localcracks in pipes, in particular of large diameter water, fuel or gasunderground pipelines. More specifically the invention concerns therepair of such pipes when the exact site to be repaired is eitherunknown or unreachable.

BACKGROUND OF THE INVENTION

In order to conduct water, fuel or gas over large distances, pipelinesthat span immense lengths are installed. Occasionally, due to corrosionor other different wearing processes, small cracks might occur in thepipes, resulting in a leakage of the fluid that flows through the pipe.Since the pressure in such pipes may reach up to 100 at., the fluid israpidly lost into the soil.

A leakage is usually discovered by a sharp pressure-drop, or by therecognition of a stain over the leakage location, indicating that alarge amount of the fluid has already been lost. Besides theenvironment-harming aspect, such leakages may cause the loss ofthousands of dollars per hour.

The repair of underground pipelines poses a series of complicatedtechnological problems considering the relevant factors, mainly,difficult accessibility to the damaged part of the pipelines if weldingor complete replacement thereof needs to be applied. This isparticularly true when considering pipelines that are thousand ofkilometers long or pipelines that lay underneath buildings and roads.

Also due to the high pressure prevailing in the pipeline, the use ofsimple adhesives and other common sealing agents had to be ruled-out.

The closest prior art known to applicants is Russian Patent No. 2063273(Appln. No. 92007181/26 filed Nov. 23, 1992), describing a method ofin-situ repair (namely from the inside of the pipe), by injectingspecific chemical substances from both sides of the damaged location.

It is the prime object of the present invention to provide a moreefficient method of in-situ repair of pipelines.

It is a further object of the invention that the actual repair processbe completed instantly, reducing to a minimum the time period duringwhich the flow through the pipeline must be discontinued.

It is a still further object of the invention to offer one or moresealing agents formulations especially suitable for the purposes theinvention herein disclosed.

SUMMARY OF THE INVENTION

According to the invention there is provided a method of repairingleakage in pipelines comprising the steps of forming a first opening inthe pipeline upstream of the leakage location, forming a second openingin the pipeline downstream of the leakage location, inserting throughthe first opening a first body, conforming the size of the pipeline,into the pipeline downstream of the first opening, filling the spacearrear of the first body with a first viscose sealing material,inserting through the first opening a second body conforming the size ofthe pipeline into the pipeline arrear of the first viscose sealingmaterial, compressing the first sealing material by applying a pressureagainst the first and the second bodies in opposite directions, causingthe first body, the compressed first sealing material and the secondbody to move in unison in the direction of the second opening, andretrieving the first and second bodies from the pipeline through thesecond opening.

The method preferably comprises the further steps of filling the spacearrear of the second body with a second viscose sealing material,inserting through the first opening a third body, conforming the size ofthe pipeline, into the pipeline arrear of the second viscose sealingmaterial, compressing the first and second sealing materials by applyinga pressure against the first and the third bodies in oppositedirections, causing the first body, the compressed first sealingmaterial, the second body, the compressed second sealing material, andthe third body to move in unison in the direction of the second opening,and retrieving the first, second and third bodies from the pipelinethrough the second opening.

The said bodies are preferably spherical, made of a semi-rigid materialsuch as Polyurethane.

BRIEF DESCRIPTION OF THE DRAWINGS

These and additional constructional features and advantages of thepresent invention will become more readily understood in the light ofthe ensuing description of preferred embodiments thereof, given by wayof example only, with reference to the accompanying drawings, wherein—

FIG. 1 is a schematic layout of a typical pipeline with a leakingportion and including a preparatory stage of the repair method accordingto a preferred embodiment of the present invention;

FIGS. 2 a-2 g represent further steps of the method; and

FIGS. 3 a and 3 b illustrate a way of nesting the respective sealingmaterials in their desired locations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 there is shown a length of pipeline 10 buried in ground G.Anywhere upstream of the pipeline 10 there is provided a shutting valve12.

A leaking location L has been identified, typically due to a hole or acrack caused by excessive corrosion developed over many years of use.

The first stage of the repairing method consists of shutting-off theflow in the pipe by the valve 12 and digging-away the ground over thepipe at two distanced locations A and B at both sides of the leakinglocation L. The distances A to L and B to L need not be equal, and infact selected according to the accessibility conditions which may changefrom one site to another.

At each location A and B, the pipe is torch-cut so as to form a firstcircular opening 14 a, and a second circular opening 14 b, respectively,both of a diameter equal to that of the pipe 10. Up-rise pipe sections(“manholes”) 16 a and 16 b are welded or otherwise affixed to the pipe10, as shown.

In the next stage (FIG. 2 a), a first spherical body C1 is insertedthrough the manhole 16 a down into the pipe 10. Right thereafter aviscose sealing material M1, the chemical formula of which will be givenbelow, is filled into the pipe, followed by a second spherical body, C2(FIG. 2 b). The bodies C1 and C2, acting as pistons, are preferably madeof a semi-rigid material such as Polyurethane so that they may easilypass through the pipe which may have bumps and protrusions along itsinner surface.

It should be emphasized at this stage that the sealing method asproposed according to the present invention can be applied by using thespherical bodies C1 and C2 and a viscose sealing material M1 only, inthe exact manner as will be described further below. However, it ishighly preferable to use a combination of materials M1 and M2, whichneeds the introduction of a third spherical body C3, as depicted in FIG.2 c. The advantages of this last-mentioned feature will be explained indetail below.

Whether or not the option of FIG. 2 c is adopted, the material M1 (aswell as M2) should be compressed during the repair process to allow itspenetration into the crack/hole H.

To this end, pressure should be applied from both sides of the arrayC2-M1-C1 (or C3-M2-C2-M1-C1). For this purpose, as seen in FIG. 2 d, themanholes 16 a and 16 b are closed and a pressurized fluid or gas ispumped into the pipe 10 in order to press the bodies C1, C2 and C3 oneagainst the other and hence compact the materials M1 and M2.

It is further requested that the pressure P₁ applied from 16 a besomewhat greater then that P₂ applied from the opposite side, whichpressure difference will cause the propagation of the arrayC3-M2-C2-M1-C1 in unison, in the direction of the manhole 16 b.

The amount of pressure P₂ that should be applied against the array ispreferably given by the formula:

P ₂ ≧a−b/D

wherein:

-   P₂—pressure (bar);-   a—an empirical factor that varies between 2.5 and 3.5;-   b—an empirical factor that varies between 0.035 and 0.045; and-   D—diameter of the pipe (meters).

During the travel of the array, as shown in FIG. 2 d and FIG. 2 e, therewill be formed on the inside surface of the pipe 10, including the crackH, a first layer of the material M1, and over it a second layer of thematerial M2. A chemical interaction between these two layers will bringto the solidification of their combination and assure the complete,durable filling of the crack H (see below).

In the further stage (FIG. 2 f) the bodies C1 and C2 (and C3—ifapplicable) are retrieved through the manhole 16 b.

The pipe sections 16 a and 16 b are then removed and replaced by covers18 a and 18 b of any conventional type (FIG. 2 g).

According to a preferred embodiment of this invention (FIG. 3 a), inorder to prevent their spreading away in different directions whilepassing from the manhole 16 a into the pipe 10, the materials M1 and M2are supplied in bags K1 and K2, respectively.

The bags are preferably made of a readily tearable sheet material, suchas cellophane or polyethylene, so that they become ruptured whenpressure is applied to the array from both sides (FIG. 3 b). Upon thetearing of the bags, the materials will intensively contact and wet theinner surface of the pipe and penetrate the cracks once reaching them.

Let us now turn to the specification of the materials recommendedaccording to an additional aspect of the present invention.

In an embodiment wherein only one sealing material M1 is employed, thematerial should be selected from the group of conventional hardeners.

In the preferred embodiment, according to which two materials M1 and M2are used, the materials may consist of a mix of a compound A, a hardenerB, a softener S, a filler mineral Z, an elastic filler E and a hardfiller D, wherein:

-   A is an organic polycondensate compound;-   B is a hardener such as phenylenediamine or diamino-difenylsulfone;-   S is a softener such as dibutyl phthalate or diphenyl phthalate;-   Z is a filler mineral such as ash of granular size ranging between 2    to 15 microns;-   E is an elastic filler such as the commercially known “Isoltherm™”    (described in U.S. Pat. No. 6,057,378) of size ranging between 4 to    7 millimeters; and-   D is a hard filler such as granules of nylon of size ranging between    1 to 4 millimeters.

The proportional amount of each of the components regarding therespective materials is given below (in weight parts).

Material M1

100 units of component A, 0-10 units of component S, 110-130 units ofcomponent Z, and component B, the amount of which is given by theformula:

B=A*λ−K ₁

Wherein:

-   K₁—an empirical factor that varies between 0 and 25; and-   A—an empirical factor that varies between 0.2-0.45.

Material M2

20-60 units of component A, 0-10 units of component S, 50-100 units ofcomponent Z and component B, the amount of which is given by theformula:

B=A*λ+K ₂

Wherein:

-   K₂—an empirical factor that varies between 0 and 30; and-   A—an empirical factor that varies between 02-0.45.

Additionally, material M2 should contain 10-15 units of component E and5-10 units of component D that are meant to penetrate the crack togetherwith material M2 and create a partial barrier between the fillingmaterials and the fluid upon restarting of the flow in the pipe, so thatthe filling will not become washed away.

The total amount of the sealing materials that should be injectedbetween two adjacent spherical bodies is given by the formula:

G≧ρD

wherein:

-   G—quantity (tons);-   ρ—an empirical factor that varies between 1 and 1.2; and-   D—internal diameter of the pipe (meters).

The time that will take for the combination of the materials M1 and M2to solidify is expected to follow the formula:

T≧γLD

Wherein:

-   T—time (hours);-   γ—an empirical factor that varies between 2.5 and 3.5;-   L—length of pipe (kilometers); and-   D—internal diameter of the pipe (meters).

After that period of time it will be safe to renew the flow through thepipe without the danger of washing away the seal layer.

In order to achieve optimal results in regard to the solidification ofthe combination of these two materials, according to a preferableembodiment, the first material M1 should contain a certain amount ofmaterial M2, and the material M2 should contain a certain amount ofmaterial M1. This could be achieved either by simply mixing all theingredients together or by using capsules that contain M1 and M2 andinserting them into the bags of M2 or M1, respectively, so that whenmaterial M1 is pushed into the crack, the capsules will break andrelease a preset quantity of the material M2.

While the invention as herein described includes numerous specifics itshould be readily apprehended by those skilled in the art to which theinvention pertains that the scope thereof should not be limited by suchspecifics but rather in and by the appended claims.

1-11. (canceled)
 12. A system for sustainable repair of a leakage in ahollow conduit, the system comprising: a) at least two bodies adapted tosubstantially fill a cross section of the hollow conduit; and b) atleast one low adhesion composition disposed between said at least twobodies; wherein said at least two bodies and said at least onecomposition are adapted to be introduced into said hollow conduit underpressure and to move along said conduit substantially without saidcomposition adhering to the conduit and without coating said conduit toa location in the vicinity of said leakage, and are further adapted torelease said at least one composition at said leakage thereby forming asustainable resilient seal at the location of said leakage.
 13. A systemaccording to claim 12, wherein said at least two bodies comprise threebodies.
 14. A system according to claim 13, wherein said at least onelow adhesion composition comprises a second composition and at least oneof a first composition and a gel.
 15. A system according to claim 14,wherein said first composition is disposed between a first body and asecond body, and wherein said second composition is disposed betweensaid second body and a third body.
 16. A system according to claim 12,wherein said at least two bodies are each selected from the groupconsisting of a spherical body, and a non-spherical body adapted to filla section of the hollow conduit.
 17. A system according to claim 14,wherein said first composition and said second composition comprise: i.at least one hardener (B), ii. at least one organic polycondensatecompound (A), and iii. at least one softener (S).
 18. A system accordingto claim 17, wherein said at least one hardener (B) is selected from thegroup consisting of phenylenediamine, diamino-diphenylsulfone,polyoxypropylene triamine and oxytriethylenetetramine.
 19. A systemaccording to claim 17, wherein said at least one organic polycondensatecompound (A) is selected from the group consisting of:polyacrylonitrile, bisphenol A and epichlorohydrine.
 20. A systemaccording to claim 17, wherein said at least one softener (S) isselected from the group consisting of: dibuthylphtalate,dioctylphtalate, polyoxypropylene triamine and diphenylphtalate.
 21. Asystem according to claim 17, further comprising at least one fillerselected from: i. a ground filler material (Z) of a particle size rangesize ranging between 2 to 15 microns, ii. an elastic filler (E) of aparticle size range between 4 to 7 millimeters, and iii. a hard filler(D) comprising organic granules of a particle size range of between 1 to4 millimeters.
 22. A system according to claim 21, wherein said at leastone filler is selected from the group consisting of fiber glass, groundrubber, ash, concrete, an elastic filler, Isoltherm™, and nylongranules.
 23. A system according to claim 21, wherein said firstcomposition comprises: i. 100 units of said at least one organicpolycondensate compound component (A), ii. 0 to 10 units of said atleast one softener (S), and iii. 110 to 130 units of said ground fillermaterial (Z).
 24. A system according to claim 22, wherein said secondcomposition comprises: i. 20 to 60 units of said at least one organicpolycondensate compound (A), ii. 0 to 10 units of said at least onesoftener (S), iii. 50 to 100 units of said ground filler material (Z),iv. said ground filler material (Z), v. said at least one hardener (B),and vi. said elastic filler (E).
 25. A method for sustainable repair ofa leakage in a hollow conduit, the method comprising the steps of i.introducing at least two bodies adapted to substantially fill a crosssection of the hollow conduit into said hollow conduit; ii. disposing atleast one composition between said at least two bodies; and iii.applying a pressure to said at least two bodies and to said at least onecomposition thereby causing said at least two bodies and said at leastone composition to move along said hollow conduit substantially withoutcoating said conduit to a location of said leakage, and further torelease said at least one composition at said location of said leakagethereby forming a sustainable resilient seal at the location of saidleakage.
 26. A method according to claim 25, wherein said introducingstep comprises: i. forming a first opening in the conduit upstream of alocation of the leakage; ii. forming a second opening in the conduitdownstream of the location of the leakage; iii. inserting at least afirst body through the first opening; iv. inserting a first compositionthrough said first opening; v. inserting a second body through saidfirst opening; and vi. applying a first pressure in a first direction tosaid first body and a second pressure to said second body in a directionopposite to said first direction thereby compressing said firstcomposition.
 27. A method according to claim 25, wherein saidintroducing step comprises: i. forming a first opening in the conduitupstream of a location of the leakage; ii. forming a second opening inthe conduit downstream of the location of the leakage; iii. inserting atleast a first body through the first opening; iv. inserting at least oneof a first composition and a gel through said first opening; v.inserting a second body through said first opening; vi. introducing asecond composition through the first opening; vii. introducing a thirdbody through said first opening; and viii. applying a first pressure ina first direction to said first body and a second pressure to said thirdbody in a direction opposite to said first direction thereby compressingsaid first composition and said second composition and thereby causingsaid at first, second and third bodies and said first and secondcompositions to move along said hollow conduit to a location of saidleakage, and further to release said first composition and said secondcomposition at said location of said leakage thereby forming a seal atthe location of said leakage.
 28. A method according to claim 27,wherein at least one of said first composition and said secondcomposition is provided in at least one bag and wherein said at leastone bag is ruptured at said location.
 29. A method according to claim27, wherein said first composition is disposed between a first body anda second body, and wherein said second composition is disposed betweensaid second body and a third body.
 30. A method according to claim 29,wherein said at least two bodies are each selected from the groupconsisting of a spherical body, and a non-spherical body adapted to filla section of the hollow conduit.
 31. A method according to claim 29,wherein said first composition and said second composition comprise: i.at least one hardener (B); ii. at least one organic polycondensatecompound (A); and iii. at least one softener (S).
 32. A method accordingto claim 31, wherein said at least one hardener (B) is selected from thegroup consisting of phenylenediamine, diamino-diphenylsulfone,polyoxypropylene triamine and oxytriethylenetetramine.
 33. A methodaccording to claim 31, wherein said at least one organic polycondensatecompound (A) is selected from the group consisting of:polyacrylonitrile, bisphenol A and epichlorohydrine.
 34. A methodaccording to claim 31, wherein said at least one softener (S) isselected from the group consisting of: dibuthylphtalate,dioctylphtalate, polyoxypropylene triamine and diphenylphtalate.
 35. Amethod according to claim 31, further comprising at least one fillerselected from: i. a ground filler material (Z) of a particle size rangesize ranging between 2 to 15 microns, ii. an elastic filler (E) of aparticle size range between 4 to 7 millimeters, and iii. a hard filler(D) comprising organic granules of a particle size range of between 1 to4 millimeters.
 36. A method according to claim 35, wherein said at leastone filler is selected from the group consisting of: fiber glass, groundrubber, ash, concrete, an elastic filler, Isoltherm™, and nylongranules.
 37. A method according to claim 35, wherein said firstcomposition comprises: i. 100 units of said at least one organicpolycondensate compound component (A); ii. 0 to 10 units of said atleast one softener (S); and iii. 110 to 130 units of said ground fillermaterial (Z).